Io - Voyager 1

Jupiter's moon Io, with Jupiter in the background

Voyager 1 image of Io against the background of Jupiter's clouds. Io is 3,600
km in diameter, about the size the Earth's Moon. The surface is coated with
sulfur compounds, making it six times brighter than the Moon. The brightness
variations seen may represent compositional and/or age differences. North is
up.
(Voyager 1, P-21162)
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